Monks who follow the way of the Shattered Knight always come to it through great trauma. The only way for one to be able to throw their mind as Shattered Knights do is for that same mind to have been fundamentally broken, hence, shattered. This isn't to say that Shattered Knights get their power through traumatic events, simply that, should a monk wish to train to be a Shattered Knight, they must have a first break.

Shattered Mind

Starting at 3rd level when you choose this subclass, you have learned to impart fragments of your consciousness into other humanoids. You can use a bonus action to spend 2 ki to have a humanoid you can see within 60 ft. of you take an action. If the humanoid is willing there is no save required, but if the humanoid is unwilling they must make a wisdom saving throw, on a success nothing happens, and on a failure you force them to take an action. You can also use this to enter a dead or unconscious humanoid, if you do so you can continue to control them, using a bonus action on each of your turns to take an action for the humanoid.

Splintered Brain

Beginning at 6th level, your repeated splintering of your consciousness has hardened your mind. You gain immunity to psychic damage, as well as having your mind read by anything short of a wish spell.

Exploding Mind

Starting at 11th level, you have perfected you shattered mind. You can now split your consciousness into any creature, you can also target 2 creatures in one bonus action, as well as being able to command three unconscious or dead creatures in one bonus action. 

Shatter Body

At 17th level, you have learned how to not only shatter your consciousness, but your body as well. You can use a bonus action to spend 6 ki and create a copy of yourself in an unoccupied space within 10 feet of you. This copy has all equipment and magic items that you do as well as the same hp, spell slots, and ki pool,it also gets its own turn, but you act under the same consciousness, meaning that only one can use Shattered Mind every round. The copy disappears 1 minute after it is created.